Screw inserting machines



May 26, 1959 E. O. PETERSON ET AL SCREW INSERTING MACHINES Filed Jan.50, 1958 4 Sheets-Sheet 1 lanl Eva/d O- Paenson May 26, 1959 Filed Jan.30, 1958 E. O. PETERSON ETAL SCREW INSERTING MACHINES 4 Sheets-Sheet 2as 5e n 73 r ag IE 17/ 69 a7 r 74 L A I 76 Z6 7 68 a2 27 g 70 J 19 rim60 67 n 69 8 6a 80 J1 \,T 'I as I g; eaq 618 ma 6 9e 63 g. 1&7 i 5 S: 64me 93 I a l 37 I 9 J I I 88 7 0| as i o 1 a7 i as J 10 m,

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May 26, 1959 E. o. PETERSON ET AL 2,883,049

SCREW INSERTING MACHINES Filed Jan. so, 1958 4 Sheets-Sheet 3 I wezzzwEra/d O- Pe-ferson Q 0 0 7? F".

United States Patent SCREW INSERTING MACHINES Evald 0. Peterson,lLynnfield Center, and John F. Smith, Braintree, Mass, assignors toCompo Shoe Machinery Corporation, Boston, Mass., a corporation ofDelaware Application January 30, 1958, Serial No. 712,193

13 Claims. (Cl. 144-32) This invention relates to screw insertingmachines, and relates more particularly to machines for securing heelsto shoes with screws.

The E. F. Small Patent No. 2,494,494 discloses a machine, that has beenwidely used for securing heels to shoes' with screws. In such machine, ashoe is placed upon an inverted last with the heel of the shoe held by apivoted clamp which is held down by air pressure. The last has a screwreceiving recess within which a screw is rotated by a screwdriver bit.The bit is driven through a withdrawing clutch by an electric motor,this clutch being of the familar Bendix type used with the startingmotors of automobiles. When the screw has reached the desired depth, alimit switch reverses the motor for withdrawing the screwdriver.

A disadvantage of the machine of said patent is that the force fordriving the screw into the heel so deflects the heel that when the limitswitch reverses the motor to back the screwdriver out, the deflectedheel under the pressure of the heel clamp follows it down so that oftenthe screwdriver does not clear the slot of the screw which is partiallyunscrewed. The deflection of the heel under the screwdriver drivingforce also results in unknown variations in the depth of the drive ofthe screw.

Another disadvantage of the machine of said patent is that the suddenreversal of the driving motor for stopping the advance of the screwoften results in the breakage of screwdrivers, screw heads and drivingcomponents. In a normal day of operation, a driving motor may bereversed as many as 1700 times, resulting in damage which may keep amachine out of operation for substantial periods of time.

A feature of our invention is that an air cylinder is used to advance ascrew as well as to clamp the shoe heel, the air pressures in the screwadvancing cylinder and in the heel clamping cylinder being so balancedthat there is no deflection of a heel under the screwdriver drivingforce.

Another feature of our invention is that instead of reversing theelectric motor which rotates the screwdriver, by a limit switch, when ascrew has been driven to the proper depth, limit switches deenergize themotor and apply electric braking to the rotor of the motor so that thelatter stops in a fraction of a revolution.

An object of our invention is to drive screws to uniform depthsregardless of types of screws and of materials in which screws aredriven.

Another object of our invention is to reduce damages to screws,screwdrivers and screwdriving components resulting from the operation ofa screw inserting machine.

Other objects of our invention are to reduce maintenance costs andout-of-operation periods of screw inserting machines.

Our invention will now be described with reference to the annexeddrawings, of which:

Fig. l is a front elevation, partially in section, of a heel attachingmachine embodying our invention;

2,888,049 Patented May 26, 1959 2 Fig. 2 is a side elevation, partiallyin section, of the machine of Fig. 1; Fig. 3 is an enlarged view,partially in section, of the upper portion of Fig. 2, with a shoe shownclamped in operating position, and

Fig. 4 is a circuit schematic of the controls of the machine.

The machine illustrated by the drawings is designed to attach plastic orwood heels to lasted uppers of shoes by flat or oval head screws ofvarious lengths and sizes.

Referring now to Figs. 1-3 of the drawings, the machine comprises a basecasting 10 on which is supported a top casting 11. The underside of thetop casting 11 has a depending boss 12 to which a bracket 13 is securedby screws 14. The bracket 13 has a vertically extending bore in which isslidably positioned a shaft 16 having a lower portion 18 of reduceddiameter which passes through an opening in the lower portion of thebracket 13 in alignment with the bore. A coiled spring 17 around theshaft portion 18 serves to bias the shaft 16 upwardly. The lower end ofthe shaft portion 18 is threaded and has nut 19 and locknut 20 screwedthereon and which serve to limit the extent to which the spring 17 canraise the shaft 16. Clamp arm 22 is pivoted at 23 to the upper end ofthe shaft 16, and has bifurcated lower portions 24 which straddle thebracket 13, and which are pivoted at 26 to a bracket 27 to which issecured by nuts 28 the threaded upper ends of rods 29. The lower ends ofthe rods 29 are threaded into clevises 30 which are pivoted tocross-member 31. The upper ends of rods 32 are threaded into thecross-member 31, and their lower portions extend through frame plate 33,and have screwed onto their lower ends nuts 34. Coiled springs 35 extendaround the rods 32 between the cross-member 31 and the plate 33. Thelower end of a piston rod 36 of clamp cylinder 37 contacts the upperside of the cross-member 31 for moving it downwardly when compressed airis admitted into the cylinder 37, against the resistance of the springs35. I

The upper end of the clamp arm 22 has attached thereto by rivets 38 anupper clamp arm 39 to the upper end of which is attached shaft 40 onwhich is positioned heel clamp member 41 to which is pivoted heel clamp42. The member 41 and arm 39 have shoulders into which is threaded ascrew 44 which can be rotated by a knurled knob 45 on its upper end toadjust the position of the clamp member 41 along the shaft 40 foradjustably raising or lowering the heel clamp. The clamp member 41 hasspaced-apart pivot holes 46 in which pivot pin 47 can selectively beplaced for adjusting the position of theheel clamp forwardly orrearwardly.

The upper end of the top casting 11 has an opening through which extendsa cap 50 which is secured by screws 51 to the casting 11. Press fittedinto the cap 50 is a bushing 52 within which is journalled screwdriverspindle 53. The spindle 53 is connected to the upper end of shaft 54,the lower end of which is attached through coupling 56 and shaft 57 topulley 58 which is driven through belt 59 by pulley 60 of electric motor61;

The lower end of the shaft 57 rests against a thrust bearing 62 thebottom of which is contacted by the upper end of piston rod 63 of drivecylinder 64 which serves to raise the screwdriver assembly as will bedescribed later. A clamp 65 is attached to a bearing 66 movablevertically with the shaft 57, has attached thereto a bracket 67 having aswitch actuating screw 68 aligned with the actuating plunger of normallyopen switch 69 which is provided for operating an electric brake in themotor 61 as will be described later. The bracket 67 also has a switchactuating screw 70 in alignment with the actuating plunger of normallyclosed switch 71 which is provided for deenergizing the motor 61.

Knob 72 of rod 73 which is threaded in frame plate 74 and in plate 75attached to the bracket 67, can be rotated to raise and lower the switchactuating screws 68 and 70 for varying the points of operation of theswitches 69 and 71 respectively. A coiled spring 76 around the rod 73between the plates 74 and 75 urges the bracket 67 downwardly. Coiledsprings 77 between the clamp 65 and frame member 78 urge the clamp 65downwardly for returning the screwdriving assembly to its retractedposition when the air in the cylinder 64 is released as will bedescribed later.

Bolt 79 threaded into bracket 13 has its inner end in a milled slot (notshown) in the sleeve of the bearing 66 for preventing the latter fromrotating.

A strap 81 attached to the clamp 65 has a switch actuating screw 80 inalignment with the actuating plunger of switch 82 which is normallyclosed, and which is a brake cutout switch as will be described later.

Foot treadle 85 is pivoted by clevis 86 to the lower end of rod 87 whichcarries switch actuator 88 which is aligned with the actuating plungerof normally open switch 89 which is provided for energizing drivesolenoid-valve 90 which admits compressed air from a conventionalcompressed air source which is not shown, into the drive cylinder 64.The switch actuator 88 is also aligned with the actuating plunger ofnormally open switch 91 which energizes solenoid-valve 92 which admitscompressed air through piping 97 into the clamp cylinder 37. Coiledspring 93 around the upper end of rod 87 and supported between framemember 94 and washer 95 under the nuts 96 threaded on the upper end ofthe rod 87, returns the treadle 85 to its normal position when pressureagainst it is released.

Structural angles 125 form horizontal, frame supporting ribs, and to oneof the angles is attached an electrical junction box 126 having aterminal strip 127 on one of its sides.

Referring now to Fig. 4 of the drawings, the switch 100 when closed,connects lines L1, L2 and L3 of the control circuit to a three-phasesupply source which is not shown. The primary winding 104 of transformer105 is connected across L1 and L2 so that the transformer is energizedwhen the switch 100 is closed. When the clamp switch 91 is closed, itconnects the clamp solenoid 92, through Wires 113, across the secondarywinding 110 of the transformer 105. When the drive switch 39 is closed,it connects, through wires 111, the drive solenoid 90 across thesecondary winding 110, and connects through wires 112 and 108 and thenormally closed motor stop switch 71, the energizing winding 101A of themagnetic starter 101 across the secondary winding 110.

A counter 119 is shunted across the energizing winding 101A, thiscounter being conventional.

When the magnetic starter 101 is energized, it closes its normally openswitches 114, 115, 116, 117 and 118, and opens its normally closedswitch 106. The switches 114, 115 and 116 connect the motor 61 to thelines L1, L2 and L3. The switches 117 and 118 provide holding circuitsfor maintaining the solenoids 90 and 92 and the magnetic starter 101energized so as to complete a cycle of operation when the switches 89and 91 open as a result of the operator having lifted his foot from thetreadle.

The normally closed brake cut-out switch 82, the normally open brakeenergizing switch 69, and the normally closed motor switch 71 areactuated by the up movement of the rotary spindle as previouslydescribed.

The switch 70, when opened, opens the previously described energizingcircuit of the magnetic starter 101.

The brake winding 102 of the motor 61 is connected through the normallyopen brake switch 69 and the normally closed switch 106 of the magneticstarter 101 and wires 120 to the supply lines L1, L2 and L3.

Valves V1 and V2 are provided for adjusting the air pressures suppliedinto the drive cylinder 64 and the clamp cylinder 37 respectively. Theair pressure would be higher in the clamp cylinder than in the drivecylinder so that the upward movement of the screwdriver bit cannotdisplace the heel clamp.

The clamp switch 91 is of the type that is opened by pressure againstits actuating plunger, and is closed when such pressure is removed.Thus, the switch 91 is open when the treadle is in the normal, upposition, and is closed when the treadle is depressed sufiiciently toremove the switch actuator 88 from its plunger.

Figs. 1 and 2 show the treadle in its fully depressed position.

The valves of the clamp and drive solenoids are of the usual type whichadmit compressed air into the clamp and drive cylinders respectively,when their respective solenoids are energized, and which permit thecylinder to exhaust the previously supplied air when their respectivesolenoids are deenergized.

Operation In operation, an operator would turn the switch to onposition. Next he would place a screw head first into the opening inlast post stern 131. A last 132 with an upper 133 thereon would beplaced on the heel post stem 131, and a heel 134 would be properlypositioned on the lasted upper. The operator would then depress thetreadle 85 about half way. This will close the switch 91 and energizethe solenoid 92, supplying air to the clamp cylinder, causing the pistonrod of the latter to bring through the cross member 31, the rods 29, theclamp arm portions 24 and 22, and upper clamp arm 39, the heel clamp 42into position on the heel. The clamp arm swings about pivot 23, and theshaft 16 moves downwardly causing the heel clamp 42 to apply avertically directed down force to the heel for holding it in positionfor screw insertion. As long as the treadle is not fully depressed, thisadjustment can be repeated until the heel is satisfactorily positioned.

The treadle is then fully depressed and closes the switch 89 whichcloses the previously described circuit to energize the magnetic starter101 which starts the motor 61, and closes the previously describedenergizing circuit of the solenoid 90 causing it to supply air to thedrive cylinder 64. The piston rod of the latter raises the thrustbearing 62, the shaft 57 and the spindle 53 while the latter is beingturned by the motor 61 through the pulleys 58 and 60. The blade of thespindle enters the slot of the screw and drives the screw into the heel.

The motor will continue to rotate the spindle, and the drive cylinderwill continue to lift the spindle until the switch actuator bracket 67contacts the plungers of the switches 69 and 71. The normally closedswitch 71 is opened and deenergizes the motor 61. The normally closedswitch 69 closes and energizes the previously described brake winding102, causing the rotor of the motor 61 to come quickly to a stop. Theswitch 71 can be opened when the switch 69 closes but it is preferredthat the switch 71 be opened just before the switch 69 closes. The timesat which the switches 69 and 71 can be actuated together can be adjustedas previously described, by rotat ing the knob 72 on the rod 73.Independent adjustment can be made by rotating the plunger contactingscrews 68 and 70.

The spindle will remain in its up position under the action of the drivecylinder 64 until the operator removes his foot from the threadle atwhich time the treadle return springs 93 disengage the switch actuatorfrom the switch 89 and deenergize the solenoid 90 which suppliedcompressed air into the drive cylinder, following which the drivecylinder exhausts the air previously supplied into it.

The clamp arm 39 will remain in heel holding position until the switchactuator 89 rises upon release of the treadle, and opens switch 91 whichdeenergizes the solenoid, allowing air to exhaust from the clampcylinder 37, following which the springs 35 cause the rods 29 to liftand to swing the heel clamp 42 away from the shoe heel.

Since the electric braking is applied through the switch 106 which isclosed by the magnetic starter 101 only when the latter and the motor 61are deenergized, the energizing circuits of the motor and brake cannotbe completed at the same time. After a screw has been driven into aheel, the brake stays on as long as the operator keeps the treadle fullydepressed.

The brake cut-out switch 82 is located and adjusted so as to be openedafter the switch 69 is closed and the switch 71 is opened, and is usedto deenergize the electric brake winding 102 when there is no shoe onthe last post stern. There being no heel to oifer resistance, thespindle will rise higher than in heel attaching operation, and will openthe switch 82, deenergizing the electric brake, and permitting anoperator to change the screwdriver bit.

What we claim as our invention is:

1. In a screw inserting machine, a work support, a rotatable spindle, ascrewdriver mounted on said spindle, means including an electric motorfor rotating said spindle in a screw driving direction, said motorhaving an electrical braking winding, means for energizing said motorand for moving said spindle towards said work support, and means fordeenergizing said motor and for energizing said braking winding aftersaid spindle has moved a predetermined distance towards said support.

2. The invention in claim 1 in which means is provided for deenergizingsaid braking winding when said spindle has moved a predetermineddistance towards said work support greater than said first mentionedpredetermined distance.

3. In a screw inserting machine, a work support, a rotatable spindle, ascrewdriver mounted on said spindle, means for rotating said spindle ina screw driving direction, means including a fluid cylinder into whichfluid under pressure is supplied for moving said spindle towards saidwork support, means for supplying fluid under pressure into saidcylinder, an operator actuated member, and means actuated after apredetermined movement of said member for causing said supply means tosupply fluid under pressure into said cylinder.

4. In a screw inserting machine, a Work support, a rotatable spindle, ascrewdriver mounted on said spindle, means for rotating said spindle ina screw driving direction, means including a first fluid cylinder intowhich fluid under pressure is supplied for clamping a work article uponsaid work support, means including a second fluid cylinder into whichfluid under pressure is supplied for moving said spindle towards saidwork support, first means for supplying fluid under pressure into saidfirst cylinder, second means for supplying fluid under pressure intosaid second cylinder, an operator actuated control member, meansactuated by the movement of said member a predetermined distance forcausing said first supply means to supply fluid into said firstcylinder, and means actuated by the movement of said member apredetermined distance greater than said first mentioned predetermineddistance for causing said second supply means to supply fluid into saidsecond cylinder.

5. The invention claimed in claim 4 in which means is provided forstarting said spindle rotating means, and in which means including meansactuated by said movement of said member said predetermined distancegreater than said first mentioned predetermined distance is provided foractuating said starting means to start said spindle rotating means.

6. In a screw inserting machine, a work support, a rotatable spindle, ascrewdriver mounted on said spindle, means including an electric motorfor rotating said spindle in a screw driving direction, means includinga first fluid cylinder into which fluid under pressure is supplied forclamping a work article on said support, means including a second fluidcylinder into which fluid under pressure is supplied for moving saidspindle towards said work support, means including a first solenoid,when energized, for supplying fluid under pressure into said firstcylinder, means including a second solenoid, when energized, for,supplying fluid under pressure into said second cylinder, meansincluding a first normally open switch for energizing said firstsolenoid, means including a sec ond normally open switch for energizingsaid second solenoid and for energizing said motor, an operator actuatedcontrol, means movable with said control for closing said first switchwhen said control has been moved a predetermined distance by anoperator, and means movable with said control for closing said secondswitch when said control has been moved a predetermined distance greaterthan said first mentioned distance by an operator.

7. The invention claimed in claim 6 in which said motor energizing meansincludes a third normally closed switch, and in which means movable withsaid spindle is provided for opening said third switch when said spindlehas moved a predetermined distance towards said work support.

8. The invention claimed in claim 7 in which said motor has an electricbraking winding, in which means including a fourth normally open switchis provided for energizing said braking winding, and in which said meansmovable with said spindle is provided with means for closing said fourthswitch.

9. The invention claimed in claim 8 in which a fifth normally closedswitch is provided and connected in series with said fourth switch, andin which said means movable with said spindle is provided with means foropening said fifth switch after said fourth switch is closed.

10. In a screw inserting machine, a work support, a rotatable spindle, ascrewdriver mounted on said spindle, means including an electric motorfor rotating said spindle in a screw driving direction, means includinga first fluid cylinder into which fluid under pressure is supplied forclamping a work article upon said work support, means including a secondfluid cylinder into which fluid under pressure is supplied for movingsaid spindle towards said work support, means including a firstsolenoid, when energized, for supplying fluid under pressure into saidfirst cylinder, means including a second solenoid, when energized, forsupplying fluid under pressure into said second cylinder, meansincluding a first normally open switch for energizing said firstsolenoid, a magnetic starter for said motor, said starter having anenergizing winding, means including a second normally open switch forenergizing said second solenoid, means including said second switch anda third normally closed switch for energizing said starter winding, saidmotor having an electric braking winding, means including a fourthnormally open switch and a fifth normally closed switch in series withsaid fourth switch and said braking winding for energizing said brakingwinding, said fifth switch being connected to said starter and beingopened by said starter when said starter winding is energized, anoperator actuated control, means movable with said control for closingsaid first switch when said control has been moved a predetermineddistance by an operator, means movable with said control for closingsaid second switch when said control has been moved a predetermineddistance greater than said first mentioned predetermined distance by anoperator, and means movable with said spindle for opening said thirdswitch and closing said fourth switch when said spindle has moved apredetermined distance towards said work support.

11. The invention claimed in claim 10 in which said means for energizingsaid braking winding includes a sixth normally closed switch in serieswith said fourth and fifth switches and said braking winding, and inwhich said means movable with said spindle includes means for openingsaid sixth switch after said fifth switch has been closed by movement ofsaid spindle towards said Work support.

12. The invention claimed in claim 11 in which said starter is providedwith switches which are closed when said starter winding is energizedand which are connected across said first and second switches forforming holding circuits.

3 13. The invention claimed in claim 10 in which said starter isprovided with switches which are closed when said starter Winding isenergized and which are connected across said first and second switchesfor forming 5 holding circuits.

No references cited.

